articulatory dynamics of stuttering / kunnampallil gejo

7/27/2019 ARTICULATORY DYNAMICS OF STUTTERING / KUNNAMPALLIL GEJO

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ARTICULATORY

DYNAMICS OFSTUTTERING

KUNNAMPALLIL

GEJO, MASLP

KUNNAMPALLIL GEJO JOHN,MASLP


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Persons who have fluency disorders can behandicapped as much more by theirreactions to their abnormal dysfluency thanthe dysfluency itself [Murray & Edwards,

1980; Van Riper, 1984].

Stuttering occurs when the forward flow ofspeech is interrupted by a motorically

disrupted sound, syllable, or word, or by thespeakers reactions thereto [Van Riper,

1982].



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Stuttering is the involuntary disruptionof a continuing attempt to produce aspoken utterance [Perkins, 1990].

Moments of stuttering are accompaniedby abnormal physiological events thatintermittently influence the processes of

respiration, phonation and/orarticulation [Denny & Smith, 1992].



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Among the varied views regarding the etiologyof stuttering, few of them consider stutteringas an articulatory disorder.

The functioning of the articulators during themoments of stuttering has been studiedextensively through the use of EMG, X-ray

motion pictures and measures of intra-oral airpressure and rate of air flow.

Thevarious abnormalities observed are:- Defective synchronization of the action potentials

of the paired musculature - such as the massetermuscles [Williams, 1955].



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A build up of muscular tension, reaching a peak nearthe termination of a block[Sheehan & Voas, 1954].

Excessive muscular activity [Shapiro, 1980].

Tremors [Van Riper, 1982].

Prolonged articulatory postures on stop consonants

[Hutchinson, 1975]. Lack of coordination between articulatory

movements and onset of phonation [Hutchinson &Watkin, 1976].

Abnormally rapid articulatory movements at themoment of release from a block [Hutchinson, 1976].



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ZIMMERMANS MODEL:

Zimmerman (1980) suggested that stutteringshould be regarded as a disorder of movementand that principles of motoric behaviour bebrought to bear on the problem.

At the level ofmotor neuron, a number of inputsfrom diverse sources are integrated and the sumof these inputs determine the background tonesand triggering threshold for coordinated

structures. This was the first physiological principle that

could be used to explain a number of diversestuttering phenomena that were explained earlyonly psychologically.KUNNAMPALLIL GEJO JOHN,MASLP


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The central commands for speech might exist asspatially coded targets, auditory targets or somehybrid.

Whatever the representation of the code, thecommands must be executed to achieve the criticalspatial temporal relationship necessary for

intelligible speech. The temporal and spatialcoordination of the articulators must be achievedthroughout a speech gesture and the fluentmovement patterns are dependent on such

relationships. These must be accomplished by the proper

neuromotor input via the cranial nerve nuclei andmotoneuron pools to proper muscles or musclesystem at the proper time.KUNNAMPALLIL GEJO JOHN,MASLP


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The movements involved in achieving these goals,the contacts made and the positions achieved

results in stimulation of many intra-oral and peri-oral receptor sites.

It is posited that when a person speaks, he usuallyoperates the respiratory, laryngeal and supra-

laryngeal systems within certain ranges of variabilityi.e. he usually stayswithin certain limits in velocities,displacements, accelerations and inter-articulatoryspatial and temporal relationships.

When these normal ranges are exceeded theafferent nerve impulses generated are presumed toincrease the gains at associated brainstem reflex

pathways. KUNNAMPALLIL GEJO JOHN,MASLP


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If excitation reaches a threshold level, then theoscillation or tonic behaviors occur. Such reflex

connections have been shown to disrupt theongoing pattern behavior byaltering afferent inputand changing muscle length and tension whichaffects the gains and phases of these pathways.

If the velocity and displacement and the spatialrelationships remain below threshold levels of

variability so as not to increase reflex affects,fluent production occurs, the stability & integrityof the system is maintained, the visual feedbackmechanisms are employed and the speech

processes continue.KUNNAMPALLIL GEJO JOHN,MASLP


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Stuttering as a defect in thecoarticulatory timing[Van Riper]:

Van Riper (1971) defined stuttering behavioras a word improperly patterned in time andthe speakers reaction thereto.

Van Riper hypothesized that the stability ofmotor patterns which maintain the integrityof syllables is somehow lacking in stutterers

due in part to over-reliance on auditoryfeedback for speech control instead ofappropriate monitoring via tactile, kinesthetic

& proprioceptive feedback.KUNNAMPALLIL GEJO JOHN,MASLP


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In addition, stutterers are thought to bedeficient in their ability to time or

integrate, long motor sequences.

Such timing is said to involve the

imposition of higher order integration toachieve the proper serial order of a largenumber of discrete motor sequences.



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Stutterers are intermittently unable to achievesuch timing thereby producing sequences

with inappropriate coarticulation. Van Riper also ruled out organic deficiencies

in these speech related functions (underlying

physiological difficulties). So he proposed that stuttering is the result of

deficiencies in

The stability of motor patterns for syllables.The ability to integrate a large number of

discrete events in correct temporal order and

speech related respiration, phonations &articulations.KUNNAMPALLIL GEJO JOHN,MASLP


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The combined result of these shortcomings is fractured syllables which is

characterized by improper coarticulatorytransitions between sounds.

For e.g. early stuttered repetitions of CVsyllables often contain the schwa vowelinstead of the target vowel (eg sa-sa-sop).

In such repetitions, it appears that thestutterer is searching for the appropriate

coarticulatory features for the sound(s) he isattempting to say.

When the correct features are achieved, the

stuttering is terminated.KUNNAMPALLIL GEJO JOHN,MASLP


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In other stuttering movements, precisetiming of transitional events between sounds

is often lost due to breaks in airflow,excessive tension and inappropriatepostures.

Agnello also said that the primary featureof stuttering is essentially within the

articulatory transition from phone tophone.



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Reason for this lack of transitions liessomewhere higher in the vocal tract

resulting from articulatory constrictions,resulting in excessive supraglottal airpressure and causes phonatory difficulties.

Van Ripers model of stuttering as a defectof co-articulatory timing is not concernedwith most of the linguistic determinants.

This model only gave a defect in timingwhich may explain some of the problemsstutterers have in maintaining rhythmic

repetitions of various speech and nons eech tasks.KUNNAMPALLIL GEJO JOHN,MASLP


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ARTICULATORY ERRORS:-

It can be studied under 2 broadheadings.

Temporal Errors:

Longer phoneme durations

Shorter phoneme durations

Longer durations between articulatoryevents

Inaccurate timing



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Spatial Errors:

Spatially restricted movements Inappropriate articulatory placements

Excessive articulatory movements

Static positioning of articulators Forceful articulatory patterns

Low velocities of articulators

Reverse muscle movements

Difficulty in stabilizing the articulatory

movementsKUNNAMPALLIL GEJO JOHN,MASLP


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TEMPORAL ERRORS:-

Longer Phoneme Duration:

Several studies have revealed increased phonemeduration in stutterers.



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Authors Method Results

Disimoni (1974) 6 stutttererswithin age rangeof 18 to 39.

Stutterers hadsignificantlygreater absolute

vowel and

consonantdurations thannon stutterers.

Montgomery & Cooke(1974) Studied part wordrepetitions in thespeech of adultstutterers using

spectrography

Results indicated alonger consonantduration in theinitial segment of

the stutteredKUNNAMPALLIL GEJO JOHN,MASLP


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Prosek &Runyan (1982)

Measured duration

of stressed vowels;extracted fromconnected speechusing spectrography

Results indicate thatstuttering group spoke

with more pauses andwith longer averagepause and vowelduration than non

stutterers. For stutteringgrouptotal durationof stressed vowel =170.6msec and for non

stuttering group- totalduration of stressed

vowel = 144.1msec.



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Kalveram & Jancke (1989) Studied vowelduration under

DAF condition

Longer vowelduration in

stuttering groupreported.

Revathi (1989) 2 normally non

fluent and 2stutteringchildren usingspectrographic

analysis forvowel duration

Results indicated

that stutteringgroup childrenhad significantlylonger vowel

duration thannormal nonfluent group.



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Shorter phoneme duration:

A few authors have reported contradictingresults compared to the above quotedstudies.

Reimann (1976) studied context

dependence of vowel duration in Germanwords.

Results: Stuttering group had shorter

vowels than controls. Also, the stutteringgroup altered the vowel duration dependingon the consonant that followed (similar to

normals).KUNNAMPALLIL GEJO JOHN,MASLP

A i l


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Article:-

Production of vowels by stuttering children and

teenagers [Howell, Williams & Young,Journal of

Fluency Disorders(1984)].

Purpose: To analyze the acoustic properties ofvowels in childrens syllable repetition to

establish whether there are differences between

children and adults which might be indicative ofthe early characteristics and progress of thedisorder.



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Method: Twenty four children and eightteenage stutterers; sample was recorded for

10 min duration.

From instances of syllable repetition..thosewhich started with voiced plosives and

where final repetition included a part of thevowel, was chosen.

Acoustic analysis of speech waveforms for

Formant frequency, duration, and intensitywere carried out.



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Results: No marked differences betweenthe formant frequency between the two

groups was seen, indicating that both groupsposition the supra glottal articulators in anequivalent positioning in order to producethe intended vowel, whether spoken fluently

or not. Durations of children's stuttered vowels are

short in comparison with those of fluent

vowels of teenagers. No difference inintensities for fluent vs dysfluent vowels inchildren; but in teenagers, fluent vowelswere higher in intensity than the dysfluent

vowels. KUNNAMPALLIL GEJO JOHN,MASLP


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No Significant Differences:-

A few authors have reported no significantdifference between stuttering group and

non-stuttering group in phoneme duration.

Klich & May (1982) studied vowels /i/, /a/,and /u/. They found no change inphoneme duration in different conditions in

stutterers.KUNNAMPALLIL GEJO JOHN,MASLP


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Healy & Ramig (1986) studied fluency instuttering and non-stuttering group duringmultiple productions of two dissimilarspeech contexts using spectrography.

Results: Duration measures for the stutteringgroup remained relatively stable duringmultiple repetitions of both short phrase andthe reading passage.



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Longer duration between

articulatory events

It is the period of inactivity between two

consecutive articulatory gestures. Adams et al (1975) and Healy (1976)

reports longer duration betweenarticulatory events in stutterers.



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Inaccurate timing

Cooper & Allen (1977) studied speechtiming control accuracy of stuttering andnon-stuttering group during speech and

non-speech activities.

Results: In general, the stuttering group

tended to be less accurate in their timingabilities than the control group.



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Spatial Errors:

The various spatial errors are:

Spatially restricted movements

Inappropriate articulatory placements

Excessive articulatory movements

Static positioning of articulators

Forceful articulatory patterns

Lower velocities of articulators

Reverse muscle movements

Difficulty in stabilizing the articulatory

movementsKUNNAMPALLIL GEJO JOHN,MASLP


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Spatially restricted movements

It has been reported that the stutterers

articulatory movements are spatially restrictedwith the velocity and the direction of movement

altered.



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Zimmerman(1980a)

Used high speedcinematography todescribe kinematics andspatial & temporal

organization of theperceptually fluentspeech gestures for 7stutterers and 7 non-

stutterers. He analyzedmovements of the lowerlip and jaw in cvc[/mam/, /pap/, /bab/].

Even in perceptuallyfluent utterances,the organization ofevents necessary for

speech productiondiffers betweengroups ofstutterers and non-

stutterers.



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Klich &May (1982) Studiedformant

frequency andrate offormanttransitions of

vowels in adultstutterers.

Resultsrevealed

temporally andspatiallyrestricted

vowelproduction.


Inappropriate articulatory


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Inappropriate articulatory

placements

Studies done by the following authors revealthat the articulatory movements in stutteringgroups are inappropriate.



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Zimmerman(1980a)

Used high speedcineradiography todescribe kinematicsand spatial & temporal

organization of theperceptually fluentspeech gestures for 6stutterers and 7 non-

stutterers and analyzedmovements of lowerlip and jaw in CVC/mam/, /pap/,

/bab/.

Asymmetrybetween lip andjaw movementsleading to

inappropriatearticulation.



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Van Riper(1982)

He studied stutteringas a temporal

disruption of thesimultaneous andsuccessiveprogramming of

muscular movementsrequired to produce aspeech sound or itslink to the nextsound in a word.

Based onspectrographic

andcineflurographicanalysis, hesuggested that

during repetitions,highlyinappropriatearticulatorypostures maybe used; both in

voiced and

unvoiced sounds.KUNNAMPALLIL GEJO JOHN,MASLP


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Mohan Murthy (1988)

[dissertation]

Studied acoustic

aerodynamicand laryngealcorrelates ofstuttering

Spectrographic

analysisindicatedarticulatoryfixations

followed byinspiratoryfrication.



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Excessive articulatory movements:

Shapiro (1980) did an extensive study andmeasured EMG activity of orbicularis oris,superior longitudinal and intrinsic laryngealmuscles of fluent and dysfluent speech of

stutterers.

Results:

Excessive muscle activity during production of

fluent as well as non-fluent utterances. Inappropriate bursts of activity before and

during periods of silence in both fluent anddysfluent utterance.



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Lack of muscle coordination during periodsof blocks, whose normal function is

reciprocal action.

These findings strongly suggest thatstutterers while speaking, experience manymovements of disruption of normalcoordination.



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Depending on the number of factorsincluding the nature, intensity, duration and

timing of disruption, its effect may or maynot result in audible or perceptible stuttering.

In some cases, disruption occurring at the

onset of a word may simply result inA slight delay in word initiation or

A pause, too brief to be identified as dysfluency



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In some other cases, the only result maybe a

Shift in Fo,

A voice breaking,Fry phonation, or

Abnormally long onset time.



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Static positioning of articulators:


Zimmerman (1980) Used high speedcineradiography

Stutterersarticulatorsstay in staticposition

during theproduction ofa phoneme.



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Zimmerman &

Pindzola (1987)

Used high speedcineflurographic

technique to recordarticulatorymovements duringfluent and

dysfluent speechfrom 4 stutterersand controlutterances from 1

normal speaker.

Inter-articularpositions occurring

in both perceptuallyfluent and dysfluentutterances ofstutterers were unlike

those nonfluentutterances of anormal speaker.

Abberant

interarticulatorpositions precededrepetitivemovements and

static posturing.KUNNAMPALLIL GEJO JOHN,MASLP


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Pindzola (1987 a) Reported thatstutterers spend

longer time instatic articulatoryposition. In other

words, the

duration of steadystate formant wasfound to belonger instutterers.



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Forceful articulatory patterns:

Webster (1974) suggested that stutterers usearticulatory patterns that are too forceful and co-articulatory movements that are too rapid. Thetransitions are too short and hence their rate ofspeech is fast.


L l i i f i l


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Lower velocities of articulators:

Studies done by various authors Adams etal (1975), Healy et al (1976) andZimmerman (1980 a) have revealed lowervelocities of articulators in stutterers.

Zimmerman (1980 a) used high speedcineradiography to describe the kinematicsand spatial and temporal organization of

perceptually fluent utterances of 6 stutterersand 17 normal speakers.

Results: lower peak velocities of articulators

in stutterers.KUNNAMPALLIL GEJO JOHN,MASLP

Article:-


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Correlation of stuttering severity and kinematics of lip

closure

(Michael, Mc Clean, Kroll; 1991)

Stutterers and non-stutterers differ in orofacialmovements associated with perceptually fluent

speech, however inconsistent results have beenobtained in this area.

Presence of some evidence that parameters ofstutterers fluent speech are associated with

stuttering severity encourages one to usecorrelation or regression analyses as approaches tounderstand anomalies in the movementcharacteristics of stutterers fluent speech.



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Aim: To evaluate possible relationshipbetween stuttering severity and

parameters of lip and jaw movementassociated with lip closure in fluentspeech.



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Results: the parameters analyzed were velocity,duration & displacement.

They noted the tendency for severestutterers to showLonger movement durations

Reduced movement velocities

Because the fluent utterances were judged,interpretation was that the more severestutterers achieved their fluency by executing

motor compensations similar to thoseacquired during speech therapy. This mayhave involved adjustments in movementduration and/or velocity.



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Reverse muscle movements:

Guitar et al (1988) studied the details of muscleactivity of 2 muscles; depressor anguli oris

[DAO] and depressor labii inferioris [LDI]. They examined lip muscle activity during the

speech production of stutterers and normalfluent speakers.

Actions of these muscles were recorded usingEMG.

The words used were peck,and puck.



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Results: EMG records indicated that non-stutterers activated DAO prior to DLI for the

production of initial /p/ whereas, stutterersreversed the sequence of onset, particularly whenthey stuttered.

These onset reversals in stutterers support the

view of stuttering as a disorder of timing.

As these reversed onsets are disruptions of thesuccession of DAO & DLI the release of the

sound may be delayed until the DAO activity ispredominantly over DLI activity and hence itdepicts an error that leads to a delay in theproduction of the sound


Difficulty in stabilizing the


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Difficulty in stabilizing thearticulatory movements:

Jansen et al (1983) investigated thedifference between stutterers and normalspeakers in phonatory and articulatory

timing during the initiation of fluentutterances of monosyllabic words. EMGrecordings of 4 articulatory muscles (glottal

vibration recordings) were done. The subjects were 15 stutterers and 17

normals.



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Parameters analyzed were

Average interval between voice onset and offset

EMG activityOnset of EMG activity in each articulator

Intra-subject variability of above measures



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Results: No significant difference betweenstuttering and non-stuttering in averageinterval times and in general stutterers weresignificantly more variable in their speechonset timing.

From this study, it was interpreted thatstutterers may have difficulty in stabilizingthe articulatory movements and the act of

speaking results in fluctuations in the speedof production of sounds and soundsequences.


Rate and rhythm of voluntary


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y yarticulatory movements:

A no of early studies investigated thestutterers ability to produce rapid speech

or speech muscle movements(diadochokinesis) or rhythmic speechmovements (rhythmokinesis).



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Spriesterbach (1940) found no statisticallysignificant differences between stuttering

and non-stuttering subjects in maximum rateof jaw opening, tongue protrusion, and lipclosure.

Experimental subjects were slightly superiorin jaw and tongue movements but slightlyinferior in lip movements.

Strother & Kriegman (1943) also foundstutterers DDK rates slightly higher for jaw

openings, repeated /t/ productions (tongue

tip to alveolar ridge), and lip closures.KUNNAMPALLIL GEJO JOHN,MASLP


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By contrast, Rickenberg (1956) found thatstutterers were significantly slower than

controls in repeatedly uttering CV syllables(/pa, ba,ma,ta,da,na,ka,ga/).

Rhythmic execution of jaw, tongue, and lipmovements was investigated by Blackburn(1931) and Seth (1934) {except for tongue

movements}. Their studies showedsignificant differences for stutterers fromnormals.



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Studies by Wulff (1935) and Strother &Kriegman (1944), however, found no

significant differences between stutterersand non-stutterers on the task (utteringrepetitive /pataka/ sequences).

Zaleski (1965) found stuttering childrendeviated significantly more from a prior

metronomic stimulus than non-stutteringchildren.



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Bloodstein (1944) and Johnson (1961)reported slower than normal reading rates in

adult stutterers. Johnson & Rosen (1937) found that

instructing stutterers to read faster than

normal resulted in more stuttering, andslower than usual rate resulted in lessstuttering.

Fransella (1965) also found that stutteringwas reduced when subjects were asked toreduce their reading rates.



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Ingham, Martin & Khul (1974) assessed theeffects on stuttering in spontaneous speech

of speaking in slower and faster rate thannormal in 3 adult stutterers.

By means of a series of lights, subjects were

given feedback every minute regarding howsuccessful they were in either speaking moreslowly or more rapidly than baseline rates.

The procedures were effective in reducingspeech rate in all three subjects.



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Zinkin (1968) studied cinefluroscopic filmsof the pharynx taken during stuttering and

reported considerable lack of coordinationbetween pharyngeal movements that wererelatively fixed while other articulators

moved. The converse was also observed; i.e., for

e.g., static articulatory gestures were

observed during periods of pharyngealmovement.


Coarticulatory errors:


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Coarticulatory errors:

A number of studies have focused uponcoarticulatory characteristics of stuttered speech.

Coarticulation refers to the normal phenomenon

during speech whereby the production of agiven sound is influenced by other sounds whichoccur before and after the sound in an utterance.

Abnormal transitional movements were firstdescribed by Stromsta (1965).



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Abnormal formant transition:

Presence of abnormal formant transitions has been

indicated in several studies. Stromsta (1965) demonstrated that the

spectrogram of stuttered speech revealed a lack ofusual falling or rising transitions seen in the

spectrograms of normal speakers. The junctureformants were either different or absent.

He also added that these children whose

dysfluencies showed anomalies in Coarticulationfailed to outgrow their stuttering, and thosechildren whose spectrograms showed normaljuncture formants had become fluent in the ten

years span since the original recordings were made.KUNNAMPALLIL GEJO JOHN,MASLP

A h h d l


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Author Method Results

Adams & Reiss(1971)

Investigated thedifference in thefluency in thefrequency of

dysfluencies ofvoiced andvoicelessphonemes instutterers.

Stated that increasedstuttering is more likely tooccur during voiceless-

voiced phonation

transition than voiced-voiceless transitions. Theyhypothesized that if thelarynx was an importantsite in the breakdown offluency, then conditionsrequiring increased

laryngeal adjustment wouldKUNNAMPALLIL GEJO JOHN,MASLP


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Webster(1974)

Comparedspectrograms of

stutterers andnon-stutterers.

Stutterers use rapidcoarticulatory movements.

Montgomery& Cooke(1976)

Analyzedperceptually andacoustically acarefully selectedset of part word

repetitions fromthe speech ofadult stutterers.

Spectrographic analysisrevealed that abnormalformant transitionscharacterized the initialsegment of the stuttered

word and the remainder ofthe word was identical to itsfluently producedcounterpart.



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From this they haveconcluded that if the

articulatory breakdownwas confined to theinitial consonant to

vowel, when present

were due to deviantformation of consonantrather than to faultytransition dynamics.


I i d h B h


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Manning & Cautal(1980)

Investigated thedysfluenciesduring voiced-

voiced, voiced-voiceless,voiceless-voiceless

phoneme tophonemephonatorytransitions. Speech

of 11 adultstutterers and amatched group ofnon-stutterers

were studied.

Both stutterersand non-stutterersgroupdemonstrated alower percentageof dysfluencies

during voiced-voiced transitionsthan during

voiced-voiceless,

voiceless-voicelessphonatorytransitions.



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Revathi (1989) Studied acoustictemporal

parameters in thespeech of 2normally non-fluent and 2

stutteringchildren.

Spectrographicanalysis revealed

that transitionduration of F2and speed oftransition of F1

showed asignificantdifferencebetween

stutterers andnon-stutterers.


Other errors observed were:-


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Other errors observed were:-

Lack of formant transition: The spectrogram ofsome dysfluent utterances were characterized byabsence of formant transition.

This indicates stutterers are unable to transit ormove from one phoneme to another.

Longer transition duration: The transition of F2was longer for dysfluent utterances than thecorresponding fluent utterances.

This implies that the time lapse between the

movement of articulator from one target toanother is long (which explains theprolongation).

Shorter transition durations: Shorter time lapsebetween movements of articulators from onetarget to another (repetitions).KUNNAMPALLIL GEJO JOHN,MASLP

Coordination Between Articulatory &


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yPhonatory Events

Mis-coordination between articulatory andphonatory events in stutterers has been reportedby several investigators.

Voice onset is a very useful measurement and itindicates the coordination of articulatory andphonatory system.

Most of the studies under this section are basedon VOT.


Longer VOT:


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Longer VOT:

Longer VOT has been reported in bothperceptually dysfluent and fluent utterances ofstutterers.

Studies comparing the VOTs of stutterers andnormals.



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Author Method Subjects Results

Agnello & Wingate(1972)

Usedpressuresensor and

voicerecorder;studied CVutterances

Agematchedgroups of

12 adultstutterers &12 normals.

Stutterers,VOTs werelonger.


Hill Gilb S A S


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Hillman & Gilbert(1977)

Spectrographic analysis

of CVstaken fromoral reading

Agematched

groups of10 adultstutterers &10 normals.

Stutterers,VOTs were

longer.(p


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Watson & Alfonso

(1982)

Spectrograp

hic analysisof 3contiguous

vowel +

consonant +vowel +consonantsequences

Age

matchedgroups of 8adultstutterers &

8 normals.

No

significantdifferencein VOTbetween

groups.


C di i f i l


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Coordination of articulatory,

laryngeal & respiratory events

Several authors have reported miscoordination ofarticulatory, laryngeal & respiratory events duringstuttering.

Adams (1974) has offered a physiologic andaerodynamic analysis of stuttering and fluency.

According to him, fluency is dependent onsmooth coordination of activities of therespiratory, phonatory, and articulatory system.



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Because evidence of disrupted motor timing

is found during stuttering (at all levels ofspeaking system) there is the possibility thatevents at each level could serve as a form ofdifficulty that triggers miscordination withthe other levels of the system.



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Mohan Murthy (1988) studied acoustic,aerodynamic, and laryngeal correlates of

stuttering. Measurements were carried out through

spectrograph, electroaerometer, and

electroglottograph.



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Observations:-

Inhalatory frications of varying durations Atypical CV & VC transition of vocal fold

cycles

Inappropriate timing of voicing

He further commented that the dysfluencies

seen during stuttering indicated severallaryngeal, aerodynamic & articulatoryabnormalities.


Th ibili f l i i


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The possibility of oral motor trainingimproving fluency is compatible with the

view that stuttering is the product of severalpoorly integrated and perhaps inadequatesubsystems of which the speech motor

control is one Oral motor therapy is designed to improve

the syllable production so that stuttering is

undermined. Current evidences suggest thata significant subgroup of those stutterershave a vulnerable speech motor system priorto the onset of perceived stuttering.



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articulatory dynamics of stuttering / kunnampallil gejo

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